Standards of Proof in Civil Litigation: An Experiment from Patent Law

Article excerpt

TABLE OF CONTENTS

I. Introduction

II. Standards of Proof--An Overview
    A. The Burden of Proof
    B. The Role and Types of Standards of Proof
    C. Previous Empirical Studies
       1. Survey Evidence
       2. Experimental Studies

III. Microsoft v. i4i and the Presumption of Validity in Patent Law

IV. Methodology and Study Design
    A. Hypotheses About i4i's Impact
    B. Why an Experiment?
    C. Study Design

V. Discussion
   A. Results
   B. Implications
   C. Directions for Future Research

VI. Conclusion

Appendix A

Appendix B

I. Introduction

Our litigation system is based upon the assumption that standards of proof matter. (1) They serve "to instruct the factfinder concerning the degree of confidence our society thinks he should have in the correctness of factual conclusions." (2) The various standards of proof reflect the legal system's judgment about the proper allocation of risk between litigants, as well as the relative importance of the issues at stake. (3) For example, in criminal cases where the defendant's liberty may be at stake, the prosecution carries the burden of proving every element of the criminal charge "beyond a reasonable doubt." (4) In contrast, "preponderance of the evidence," a much less stringent standard, is most common in civil cases. (5) The third main standard, "clear and convincing evidence," is an intermediate standard employed in civil litigation when "the individual interests at stake ... are both 'particularly important' and 'more substantial than mere loss of money.'" (6)

But despite the perceived importance of standards of proof, few empirical studies have tested lay jurors' understanding and application of standards of proof, particularly in civil litigation. (7) Specifically, to our knowledge, there has not been a large-scale study of a demographically representative population comparing jurors' decisions when confronted with the two standards of proof used in civil litigation: (1) preponderance of the evidence, and (2) clear and convincing evidence. (8)

Patent law recently presented an opportunity to assess the impact of varying the standard of proof in civil litigation. Under Section 282 of the Patent Act, every claim in a patent issued by the U.S. Patent and Trademark Office ("USPTO") is presumed to be valid. (9) This same statute also provides that "[t]he burden of establishing invalidity of a patent or any claim thereof shall rest on the party asserting such invalidity." (10) However, the statute fails to specify the standard of proof necessary to overcome this presumption of validity.

In a recent case, Microsoft Corp. v. i4i Ltd. Partnership ("i4i"), the U.S. Supreme Court heard competing arguments regarding the proper standard of proof for finding a patent invalid. (11) Microsoft argued that the preponderance of the evidence standard should apply, at least when the USPTO had not considered the prior art that allegedly invalidated the patent. (12) But the Court unanimously affirmed the U.S. Court of Appeals for the Federal Circuit's ("Federal Circuit") longstanding interpretation that invalidity must be proven "by clear and convincing evidence." (13)

However, the Court also held that if the party challenging a patent's validity could introduce new evidence in litigation that had not previously been considered by the USPTO during the patent's examination, then "the challenger's burden to persuade the jury of its invalidity defense by clear and convincing evidence may be easier to sus-sustain." (14) In such situations, the jury should be instructed that "it has heard evidence that the [US]PTO had no opportunity to evaluate before granting the patent" and to "consider that fact when determining whether an invalidity defense has been proved by clear and convincing evidence." (15) But at the same time, the Court declined "to endorse any particular formulation" for such an instruction. (16)

Both the parties in i4i and the Court apparently assumed that the standard of proof would affect lay jurors' decisions regarding invalidity, at least on the margins. …